1. Field of the Invention
The present invention relates to an energy resource-grid-load automatic control system of smart microgrid and control methods thereof, which belong to the field of microgrid control and electrical technology.
2. The Prior Arts
With the economic development and the progress of science and technology, the decentralized and small-scale power systems have been gradually replaced by central stations with large-capacity and high-parameter units and by the modes of extra-high voltage long distance transmission and large grid interconnected and centralized power supply in pursuit of scale benefit in the industrial era. However, there are still some drawbacks of the main modes of generation, transmission and distribution of electric energy in response to the flexibility of load variation and the safety of power supply. In recent years, the energy crisis and the power failure of large power grids occur frequently. In addition, provinces in China have taken measures for power rationing to different degrees in summer in recent years. The power crisis and the large-scale power failure reveal that the existing huge power systems have defects. (1) It is possible that the fault of any point in the large power grids seriously affects the whole power grid, and even results in the large-scale power failure and the power grid collapse. (2) The large power grids cannot flexibly follow the load variation. With the increase of the load peak-valley difference, the load rate of the power grid declines year by year, and the utilization rate of power generation and transmission facilities tends towards decrease. (3) In some remote areas, the power supply is not ideal, because of long distance from power systems, harsh natural conditions, too large investment in power transmission and distribution construction or infeasibility of erection of power transmission and distribution lines. (4) In recent years, large power grids are often the targets of terrorist attacks and wars, and consequences will be unimaginable once these large power grids are destroyed. Moreover, the global primary energy suffers from exhaustion increasingly, and the environmental pollution caused by power generation, including acid rain, greenhouse effect and electromagnetic pollution, is becoming more and more obvious.
Considering the serious environmental problems, the supply safety of future energy sources and the reform of electric power systems, people have to pursue high efficient energy conversion, reduce emissions of hazardous substances, seek alternative fuels, implement graded use of energy and utilize a small-scale distributed power generation system, in order to meet the above-mentioned requirements.
If a distributed renewable energy microgrid is accessed to a distribution network, the structure of the power grid will be greatly affected, and accordingly the power grid including the microgrid needs to be replanned. However, conventional problems of power grid planning, such as load optimization, substation optimization and reactive power optimization, and a series of new problems of microgrid access points and access capacity optimization remain to be solved. Due to the bidirectional energy transfer between the microgrid and the large power grids, and the intermittence and the fluctuation of a distributed power source, the protection and the control strategy of the microgrid including the distributed power source differ from those of conventional power grids. It is difficult that the diversified demands of distribution users for the quality of power supply are satisfied as far as possible under the condition of stable operation of the large power grids. However, the renewable energy power generation and the energy storage equipment in the microgrid cannot be coordinated well, and the intelligent control of loads cannot be achieved in the prior art, thereby greatly hampering the development of the distributed power generation system.